JPH09223932A - High frequency mixer circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency mixer for not generating a resonance phenomenon inside an intermediate frequency signal band. SOLUTION: In this high frequency mixer circuit for which a high frequency signal input terminal or a local oscillation signal input terminal is a waveguide interface, an MIM capacitor 20 is provided on a position where an electric length to a first ground point 15 to be one reflection point for causing resonance on a first microstrip line 13 for propagating high frequency signals is equal to or less than 1/4 wavelength of the intermediate frequency signal band. Also, the MIM capacitor 21 is provided on the position where the electric length to a second ground point 16 to be one reflection point for causing the resonance on a second microstrip line 14 for propagating local oscillation signals is equal to or less than 1/4 wavelength of the intermediate frequency signal band. By changing a distance between the reflection points for causing the resonance, a resonance frequency is moved to the outside of the band of a desired intermediate frequency signal frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency mixer circuit in which a high frequency signal input terminal or a local oscillator signal input terminal is a waveguide interface.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a conventional high frequency mixer circuit. In the figure, 1 is a high-frequency signal input terminal,
2 is a local signal input terminal, 3 is an intermediate frequency signal output terminal, 4
Is a first waveguide / microstrip line converter, 5 is a second waveguide / microstrip line converter, 6 is a transmission line, and 7 is a field effect transistor (Field Ef).
A complete transistor, hereinafter referred to as a FET. ) Mixer or diode mixer, 8 is a first low pass filter (hereinafter referred to as LPF), 9 is a second LPF, 10 is a high frequency signal input matching circuit, 11 is a local signal input matching circuit, 1
2 is an output matching circuit for intermediate frequency signals, 13 is a first microstrip line, 14 is a second microstrip line, 15 is a first ground point, and 16 is a second ground point.

Next, the operation will be described. The high-frequency signal input from the high-frequency signal input terminal 1 is converted from the waveguide mode to the microstrip line mode by the first waveguide / microstrip line converter 4, and the first microstrip line 13 and the high-frequency signal are converted. Propagates to the input matching circuit 10 and is applied to the FET mixer or the diode mixer 7. The local oscillator signal input from the local oscillator signal input terminal 2 is converted from the waveguide mode to the microstrip line mode by the second waveguide / microstrip line converter 5, and the second microstrip line 14
And is propagated through the local signal input matching circuit 11 and applied to the FET mixer or the diode mixer 7. The FET mixer or the diode mixer 7 converts a high frequency signal into an intermediate frequency signal which is a frequency component of the difference between the high frequency signal and the local oscillation signal. Intermediate frequency signal is output matching circuit 1 for intermediate frequency signal
2, propagated through the transmission line 6, and taken out from the intermediate frequency signal output terminal 3. The first LPF 8 is grounded at the first grounding point 15 and is provided to selectively pass the intermediate frequency signal generated by the FET mixer or the diode mixer 7 and prevent it from propagating to the high frequency signal input matching circuit 10 side. It has been done. The second LPF 9 is grounded at the second grounding point 16, and in order to selectively pass the intermediate frequency signal generated by the FET mixer or the diode mixer 7 and prevent the intermediate frequency signal from propagating to the local signal input matching circuit 11 side. It is provided.

[0004]

In the conventional high frequency mixer circuit, the reflection component of the intermediate frequency signal is generated at the first ground point 15, and the first LPF 8 and the high frequency signal input matching circuit 1 are provided.
0, propagates through the first microstrip line 13,
It reaches the waveguide / microstrip line converter 4. Since the first waveguide / microstrip line converter 4 is open with respect to the intermediate frequency signal, a reflected wave for the leakage component of the intermediate frequency signal is generated due to the mismatch. Therefore, the first ground point 15 and the first waveguide / microstrip line converter 4 serve as reflection points, and the first ground point 15 and the first waveguide / microstrip line converter 4 are connected to each other. There is a problem in that resonance occurs in which the electric length l ₁ of ₁ becomes a quarter wavelength, and the resonance appears in the band of the desired intermediate frequency signal depending on the length of the electric length l ₁ .
In addition, the reflection component of the intermediate frequency signal is generated also at the second ground point 16, and the second LPF 9 and the local signal input matching circuit 1
Propagating through the first and second microstrip lines 14,
The waveguide / microstrip line converter 5 of FIG. Since the second waveguide / microstrip line converter 5 is open for the intermediate frequency signal, a reflected wave for the intermediate frequency signal leakage component is generated due to the mismatch.
Therefore, the second ground point 16 and the second waveguide / microstrip line converter 5 serve as reflection points, and the second ground point 16 and the second waveguide / microstrip line converter 5 are connected to each other. There is a problem that resonance occurs in which the electric length l _{2 of the above} is 1/4 wavelength, and the resonance appears in the band of the desired intermediate frequency signal depending on the length of the electric length l ₂ .

The present invention has been made to solve the above problems, and an object thereof is to prevent in-band resonance of a desired intermediate frequency signal of a high frequency mixer circuit.

[0006]

A high frequency mixer circuit according to a first aspect of the present invention allows a high frequency signal to pass through a first microstrip line through which a high frequency signal is propagated, and a capacitor having a capacitance for cutting off an intermediate frequency signal to resonate. It is provided at a position within 1/4 wavelength of the intermediate frequency signal band in terms of electrical length from the first grounding point which is one reflection point causing the local oscillation signal, and is further transmitted to the second microstrip line through which the local oscillation signal is propagated. To cause resonance by providing a capacitor having a capacity for passing the intermediate frequency signal and blocking the intermediate frequency signal from the second ground point, which is one reflection point that causes resonance, at a position within 1/4 wavelength of the intermediate frequency signal band in terms of electrical length By changing the distance between the reflection points,
The resonance frequency is moved outside the band of the desired intermediate frequency signal.

A high frequency mixer circuit according to a second aspect of the present invention is the high frequency mixer circuit according to the first aspect, wherein a chip capacitor, MIM (M
et al Insulator Metal, and inter digital (Inter Digit)
al, hereinafter referred to as ID. ) A capacitor is used to change the distance between the reflection points that cause resonance to move the resonance frequency outside the band of the desired intermediate frequency signal.

In the high-frequency mixer circuit of the third invention, the first microstrip line through which the high-frequency signal is propagated passes the high-frequency signal, and the coupler for cutting off the intermediate-frequency signal serves as one reflection point which causes resonance. Provided at a position within 1/4 wavelength of the intermediate frequency signal band from the grounding point of the terminal, and further pass the local signal to the second microstrip line through which the local signal is propagated and block the intermediate frequency signal. The coupler is installed at a position that is less than a quarter wavelength of the intermediate frequency signal band in terms of electrical length from the second ground point, which is one reflection point causing resonance, and the resonance point is changed by changing the distance between the reflection points causing resonance. The frequency is moved outside the band of the desired intermediate frequency signal.

In the high frequency mixer circuit of the fourth invention, the intermediate frequency signal is passed through the first microstrip line through which the high frequency signal is propagated to the first ground point which is one reflection point causing resonance. Is connected to a third LPF having a grounding point at a position where the electrical length of is less than 1/2 wavelength of the intermediate frequency signal band, and the intermediate frequency signal is transmitted to the second microstrip line through which the local oscillator signal is propagated. A fourth LPF having a grounding point is connected at a position where the electric length up to the second grounding point, which is one of the reflection points that causes the resonance to occur, is equal to or less than 1/2 wavelength of the intermediate frequency signal band, and the resonance is caused. The resonance frequency is moved outside the band of the desired intermediate frequency signal by changing the distance between the reflection points.

The high frequency mixer circuit of the fifth invention is
The intermediate frequency signal is terminated in the first microstrip line through which the high frequency signal is propagated, and the electrical length is 1 /
The first short stub having four wavelengths is connected to the first terminating resistor whose one end is connected, and further, the intermediate frequency signal is terminated to the second microstrip line through which the local oscillation signal is propagated. Resonance occurs by connecting the second terminating resistor, which is connected to one end of the second short stub that is ¼ wavelength of the local oscillation signal, and connecting the terminating resistors in parallel between the reflection points that cause resonance. Is configured to prevent.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. 1 is a block diagram showing a high frequency mixer circuit according to a first embodiment of the present invention. 1 in the figure
Up to 16 are similar to the block diagram 7 showing the conventional high frequency mixer circuit. Reference numeral 17 is a first chip capacitor, and 18 is a second chip capacitor.

Next, the operation of the above high frequency mixer circuit will be described. The high frequency signal input from the high frequency signal input terminal 1 is supplied to the first waveguide / microstrip line converter 4
Is converted from a waveguide mode to a mode of a microstrip line by means of propagating through the first microstrip line 13, the first chip capacitor 17 and the high frequency signal input matching circuit 10 and applied to the FET mixer or the diode mixer 7. It The local oscillator signal input from the local oscillator signal input terminal 2 is converted from the waveguide mode to the microstrip line mode by the second waveguide / microstrip line converter 5, and the second microstrip line 1
4, propagated through the second chip capacitor 18 and the local oscillator signal input matching circuit 11 and applied to the FET mixer or the diode mixer 7. The FET mixer or the diode mixer 7 converts a high frequency signal into an intermediate frequency signal which is a frequency component of the difference between the high frequency signal and the local oscillation signal. The intermediate frequency signal propagates through the intermediate frequency signal output matching circuit 12 and the transmission line 6, and is taken out from the intermediate frequency signal output terminal 3.

On the other hand, the intermediate frequency signal leaking to the high frequency signal input matching circuit 10 side is directly propagated to the high frequency signal input matching circuit 10 because of the first LPF 8 that selectively passes the intermediate frequency signal. There is no such thing. However, the intermediate frequency signal propagating through the first LPF 8 causes a reflected wave at the ground point 15, and reaches the first chip capacitor 17 via the first LPF 8 and the high frequency signal input matching circuit 10. Since the capacitance of the first chip capacitor 17 is set so as to pass the high frequency signal and block the intermediate frequency signal, the reflected wave of the reached intermediate frequency signal is further reflected and the first chip capacitor 17 and the first ground point 15 are connected together. Resonance occurs between them. Here, from the first ground point 15 to the first chip capacitor 17
By setting the electric length l _{1 up} to 1/4 wavelength of the intermediate frequency signal band or less, the resonance frequency can be moved outside the band of the intermediate frequency signal frequency. Further, the intermediate frequency signal leaking to the local signal input matching circuit 11 side cannot be directly propagated to the local signal input matching circuit 11 because of the second LPF 9 that selectively passes the intermediate frequency signal. Absent. However, the intermediate frequency signal propagating through the second LPF 9 causes a reflected wave at the second ground point 16 to cause a second LP signal.
The second chip capacitor 18 is reached via F9 and the input matching circuit 11 for local oscillator signal. The capacitance of the second chip capacitor 18 is set so as to pass the local signal and block the intermediate frequency signal, so that the reflected wave of the reached intermediate frequency signal is further reflected and the second ground point 16 and Resonance occurs between. Here, by setting the electrical length l ₂ from the second ground point 16 to the second chip capacitor 18 to be ¼ wavelength or less of the intermediate frequency signal band, the resonance frequency is moved to the outside of the intermediate frequency signal frequency band. Can be made.

Thus, the electrical length from the first ground point 15 to the first waveguide / microstrip line converter 4 and the second ground point 16 to the second waveguide / microstrip line. Even when the electrical length up to the converter 5 cannot be made equal to or less than ¼ wavelength of the intermediate frequency signal band, the use of the chip capacitor can prevent in-band resonance of the intermediate frequency signal desired by the high frequency mixer circuit.

Embodiment 2 2 is a block diagram showing a high frequency mixer circuit according to a second embodiment of the present invention.
In the figure, 1 to 16 show the same as the block diagram 7 showing the conventional high frequency mixer circuit. 19 is the first MI
M capacitor, 20 is a second MIM capacitor.

Next, the operation of the high frequency mixer circuit will be described. The high frequency signal input from the high frequency signal input terminal 1 is supplied to the first waveguide / microstrip line converter 4
Is converted from the waveguide mode to the mode of the microstrip line by the propagation through the first microstrip line 13, the first MIM capacitor 19 and the high frequency signal input matching circuit 10 and applied to the FET mixer or the diode mixer 7. It The local oscillator signal input from the local oscillator signal input terminal 2 is converted from the waveguide mode to the microstrip line mode by the second waveguide / microstrip line converter 5, and the second microstrip line 1
4, propagated through the second MIM capacitor 20 and the local oscillator signal input matching circuit 11 and applied to the FET mixer or the diode mixer 7. The FET mixer or the diode mixer 7 converts a high frequency signal into an intermediate frequency signal which is a frequency component of the difference between the high frequency signal and the local oscillation signal. The intermediate frequency signal propagates through the intermediate frequency signal output matching circuit 12 and the transmission line 6, and is taken out from the intermediate frequency signal output terminal 3.

On the other hand, the intermediate frequency signal leaking to the high frequency signal input matching circuit 10 side is directly propagated to the high frequency signal input matching circuit 10 because of the first LPF 8 that selectively passes the intermediate frequency signal. There is no such thing. However, the intermediate frequency signal propagating through the first LPF 8 causes a reflected wave at the first grounding point 15, and passes through the first LPF 8 and the high frequency signal input matching circuit 10 to generate the first MIM capacitor 1
Reach 9. Since the first MIM capacitor 19 is formed so as to pass a high-frequency signal and cut off the intermediate-frequency signal, the reflected wave of the intermediate-frequency signal that reaches the first MIM capacitor 19 is further reflected, and the first ground point 15 and Resonance occurs between. Here, the electrical length l ₁ from the first ground point 15 to the first MIM capacitor 19 is set to 1 / m of the intermediate frequency signal band.
By setting the wavelength to 4 wavelengths or less, the resonance frequency can be moved outside the band of the intermediate frequency signal frequency. Also,
The intermediate frequency signal leaking to the local matching signal input matching circuit 11 side does not directly propagate to the local matching signal input matching circuit 11 because of the second LPF 9 that selectively passes the intermediate frequency signal. However, the intermediate frequency signal propagating through the second LPF 9 causes a reflected wave at the second ground point 16, and is transmitted to the second MIM capacitor 20 via the second LPF 9 and the local signal input matching circuit 11. To reach. Second MIM
Since the capacitor 20 is formed so as to pass the local signal and block the intermediate frequency signal, the reflected wave of the reached intermediate frequency signal is further reflected and reaches the second ground point 16. Resonance occurs. Here, the second ground point 1
By setting the electrical length l ₂ from 6 to the second MIM capacitor 20 to be ¼ wavelength or less of the intermediate frequency signal band, the resonance frequency can be moved outside the intermediate frequency signal frequency band.

Thus, the electrical length from the first ground point 15 to the first waveguide / microstrip line converter 4 and the second ground point 16 to the second waveguide / microstrip line. Even when the electrical length up to the converter 5 cannot be made equal to or less than ¼ wavelength of the intermediate frequency signal band, the use of the MIM capacitor can prevent the in-band resonance of the intermediate frequency signal desired by the high frequency mixer circuit.

Further, since the first MIM capacitor 19 and the second MIM capacitor 20 are used as the capacitors, MI is used when manufacturing the microstrip line.
Since the M capacitor can be formed, the number of parts can be reduced as compared with the configuration of the first embodiment using the chip capacitor, and the assembling workability can be improved. Also, MIM
Since the capacitor can have the same width as the microstrip line, the size can be made smaller than the configuration of the first embodiment in which the size is limited by the chip capacitor.

Embodiment 3 3 is a block diagram showing a high frequency mixer circuit according to a third embodiment of the present invention.
In the figure, 1 to 16 show the same as the block diagram 7 showing the conventional high frequency mixer circuit. 21 is the first ID
A capacitor, 22 is a second ID capacitor.

Next, the operation of the high frequency mixer circuit will be described. The high frequency signal input from the high frequency signal input terminal 1 is supplied to the first waveguide / microstrip line converter 4
Is converted from the waveguide mode to the mode of the microstrip line by means of propagating through the first microstrip line 13, the first ID capacitor 21 and the high frequency signal input matching circuit 10 and applied to the FET mixer or the diode mixer 7. It The local oscillator signal input from the local oscillator signal input terminal 2 is converted from the waveguide mode to the microstrip line mode by the second waveguide / microstrip line converter 5, and the second microstrip line 14,
It propagates through the second ID capacitor 22 and the input matching circuit 11 for local oscillation signal and is applied to the FET mixer or the diode mixer 7. The FET mixer or the diode mixer 7 converts a high frequency signal into an intermediate frequency signal which is a frequency component of the difference between the high frequency signal and the local oscillation signal. The intermediate frequency signal propagates through the intermediate frequency signal output matching circuit 12 and the transmission line 6, and is taken out from the intermediate frequency signal output terminal 3.

On the other hand, the intermediate frequency signal leaking to the high frequency signal input matching circuit 10 side must be directly propagated to the high frequency signal input matching circuit 10 for the first LPF 8 that selectively passes the intermediate frequency signal. There is no. But the first L
A reflected wave is generated at the first grounding point 15 of the intermediate frequency signal propagating through the PF 8, and reaches the first ID capacitor 21 via the first LPF 8 and the high frequency signal input matching circuit 10. Since the first ID capacitor 21 is formed so as to have a capacity that allows high-frequency signals to pass therethrough and blocks intermediate-frequency signals, the reflected waves of the intermediate-frequency signals that have reached are further reflected and the first ground point 15 and Resonance occurs between.
Here, from the first ground point 15 to the first ID capacitor 2
By setting the electrical length l _{1 up} to ₁ to not more than ¼ wavelength of the intermediate frequency signal band, the resonance frequency can be moved outside the intermediate frequency signal frequency band. Further, the intermediate frequency signal leaking to the input matching circuit 11 side for the local signal is due to the second LPF 9 which selectively passes the intermediate frequency signal,
It does not directly propagate to the local signal input matching circuit 11. However, the intermediate frequency signal propagated through the second LPF 9 causes a reflected wave to be generated at the second ground point 16, and
F9, via the input matching circuit 11 for the local oscillator signal to the second I
The D capacitor 22 is reached. Second ID capacitor 2
Since 2 is formed so as to have a capacity for passing the local signal and blocking the intermediate frequency signal, the reflected wave of the reached intermediate frequency signal is further reflected and resonates with the second ground point 16. Happens. Here, the resonance frequency is moved outside the band of the intermediate frequency signal frequency by setting the electrical length l ₂ from the second ground point 16 to the second ID capacitor 22 to be ¼ wavelength or less of the intermediate frequency signal band. Can be made.

Thus, the electrical length from the first ground point 15 to the first waveguide / microstrip line converter 4 and the second ground point 16 to the second waveguide / microstrip line Even if the electrical length up to the converter 5 cannot be set to be equal to or less than ¼ wavelength of the intermediate frequency signal band, the use of the ID capacitor can prevent the in-band resonance of the intermediate frequency signal desired by the high frequency mixer circuit.

Further, since the first ID capacitor 21 and the second ID capacitor 22 are used as the capacitors, the ID is used when the pattern of the microstrip line is manufactured.
Capacitors can be formed at the same time, the number of parts can be reduced as compared with the configuration of the first embodiment using a chip capacitor, and the assembling workability can be improved.
The manufacturing process is simplified as compared with the configuration of the second embodiment,
Can be manufactured at a lower cost. Further, since the capacitance of the ID capacitor is determined by the pattern dimension accuracy, it is possible to obtain a stable characteristic with higher accuracy and because the capacitance independent of temperature can be secured.

Embodiment 4 Fourth Embodiment FIG. 4 is a block diagram showing a high frequency mixer circuit according to a fourth embodiment of the present invention.
In the figure, 1 to 16 show the same as the block diagram 7 showing the conventional high frequency mixer circuit. Reference numeral 23 is a first coupler, and 24 is a second coupler.

Next, the operation of the above high frequency mixer circuit will be described. The high frequency signal input from the high frequency signal input terminal 1 is supplied to the first waveguide / microstrip line converter 4
Is converted from the waveguide mode to the mode of the microstrip line by the first microstrip line 13, the first coupler 23, and the input matching circuit 10 for high frequency signals.
Is applied to the FET mixer or the diode mixer 7. The local oscillator signal input from the local oscillator signal input terminal 2 is converted from the waveguide mode to the microstrip line mode by the second waveguide / microstrip line converter 5, and the second microstrip line 14, The signal propagates through the second coupler 24 and the local signal input matching circuit 11 and is applied to the FET mixer or the diode mixer 7. The FET mixer or the diode mixer 7 converts a high frequency signal into an intermediate frequency signal which is a frequency component of the difference between the high frequency signal and the local oscillation signal. The intermediate frequency signal propagates through the intermediate frequency signal output matching circuit 12 and the transmission line 6, and is taken out from the intermediate frequency signal output terminal 3.

On the other hand, the intermediate frequency signal leaking to the side of the high frequency signal input matching circuit 10 must be directly propagated to the high frequency signal input matching circuit 10 for the first LPF 8 that selectively passes the intermediate frequency signal. There is no. But the first L
A reflected wave is generated at the first ground point 15 of the intermediate frequency signal propagating through the PF 8, and reaches the first coupler 23 via the first LPF 8 and the high frequency signal input matching circuit 10. The first coupler 23 is impedance-matched at a high frequency signal frequency, and the reflected wave of the intermediate frequency signal that has arrived is further reflected, so that resonance occurs with the first ground point 15. Here, the electrical length l ₁ from the first ground point 15 to the first coupler 23 is ¼ of the intermediate frequency signal band.
The resonance frequency can be moved outside the band of the intermediate frequency signal frequency by setting the wavelength to the wavelength or less. Further, the intermediate frequency signal leaking to the local signal input matching circuit 11 side cannot be directly propagated to the local signal input matching circuit 11 because of the second LPF 9 that selectively passes the intermediate frequency signal. Absent. However, the intermediate frequency signal propagating through the second LPF 9 generates a reflected wave at the second ground point 16,
To the second coupler 24 via the LPF 9 and the local signal input matching circuit 11. The second coupler 24 is impedance-matched at the local signal frequency, and the reflected wave of the arriving intermediate frequency signal is further reflected.
Resonance occurs with the ground point 16 of the. Here, the resonance frequency is moved outside the band of the intermediate frequency signal frequency by setting the electrical length l ₂ from the second ground point 16 to the second coupler 24 to be ¼ wavelength or less of the intermediate frequency signal band. be able to.

Thus, the electrical length from the first ground point 15 to the first waveguide / microstrip line converter 4 and the second ground point 16 to the second waveguide / microstrip line Even when the electrical length up to the converter 5 cannot be made equal to or less than ¼ wavelength of the intermediate frequency signal band, the use of the coupler can prevent in-band resonance of the intermediate frequency signal desired by the high frequency mixer circuit.

Also in this case, since the coupler can be formed at the same time when the pattern of the microstrip line is manufactured, the number of parts can be reduced and the assembling workability can be improved as compared with the structure of the first embodiment. And yet,
The manufacturing process is simplified as compared with the configuration of the second embodiment,
Can be manufactured at a lower cost. Further, since the coupler can be made smaller than the width of the microstrip line, it can be made smaller than the configuration of the first embodiment in which the size is limited by the chip capacitor.

Embodiment 5 5 is a block diagram showing a high frequency mixer circuit according to a fifth embodiment of the present invention.
In the figure, 1 to 16 show the same as the block diagram 7 showing the conventional high frequency mixer circuit. 25 is the third LP
F and 26 are fourth LPFs, 27 is a third ground point, and 28 is a fourth ground point.

Next, the operation of the above high frequency mixer circuit will be described. The high frequency signal input from the high frequency signal input terminal 1 is supplied to the first waveguide / microstrip line converter 4
Is converted from the waveguide mode to the mode of the microstrip line, propagates through the first microstrip line 13 and the high-frequency signal input matching circuit 10, and is applied to the FET mixer or the diode mixer 7. The local oscillator signal input from the local oscillator signal input terminal 2 is converted from the waveguide mode to the microstrip line mode by the second waveguide / microstrip line converter 5, and the second microstrip line 14 and The FET mixer or the diode mixer 7 is propagated through the local matching signal input matching circuit 11.
Is applied to FET mixer or diode mixer 7
Converts the high frequency signal into an intermediate frequency signal which is a frequency component of the difference between the high frequency signal and the local oscillation signal. The intermediate frequency signal propagates through the intermediate frequency signal output matching circuit 12 and the transmission line 6, and is taken out from the intermediate frequency signal output terminal 3.

On the other hand, the intermediate frequency signal leaking to the high frequency signal input matching circuit 10 side must be directly propagated to the high frequency signal input matching circuit 10 for the first LPF 8 that selectively passes the intermediate frequency signal. There is no. But the first L
A reflected wave is generated at the first grounding point 15 of the intermediate frequency signal propagating through the PF 8, and reaches the third grounding point 27 via the first LPF 8, the high frequency signal input matching circuit 10 and the third LPF 25. To do. Since the reflection of the intermediate frequency signal reaching the third ground point 27 is further reflected, the ground point 15
Resonance occurs between. Here, by arranging the third grounding point 27 at a position where the electrical length l ₁ from the first grounding point 15 to the third grounding point 27 can be set to 1/2 wavelength or less of the intermediate frequency signal band, resonance occurs. The frequency can be moved outside the band of the intermediate frequency signal frequency. Further, the intermediate frequency signal leaking to the local signal input matching circuit 11 side cannot be directly propagated to the local signal input matching circuit 11 because of the second LPF 9 that selectively passes the intermediate frequency signal. Absent. However, the intermediate frequency signal propagating through the second LPF 9 causes a reflected wave at the second ground point 16, and passes through the second LPF 9, the local signal input matching circuit 11, and the fourth LPF 26 to the fourth LPF 26. To the ground contact point 28 of Since the reflected wave of the intermediate frequency signal reaching the fourth ground point 28 is further reflected,
Resonance occurs with the second ground point 16. Here, the second
By arranging the fourth grounding point 28 at a position where the electrical length l ₂ from the grounding point 16 to the fourth grounding point 28 can be set to ½ wavelength or less of the intermediate frequency signal band, the resonance frequency is set to the intermediate frequency signal. It can be moved outside the frequency band.

Thus, the electrical length from the first ground point 15 to the first waveguide / microstrip line converter 4 and the second ground point 16 to the second waveguide / microstrip line Even if the electrical length up to the converter 5 cannot be less than ¼ wavelength of the intermediate frequency signal, the grounded LP
By using F, in-band resonance of the intermediate frequency signal desired by the high frequency mixer circuit can be prevented.

Embodiment 6 FIG. 6 is a block diagram showing a high frequency mixer circuit according to a sixth embodiment of the present invention.
In the figure, 1 to 16 show the same as the block diagram 7 showing the conventional high frequency mixer circuit. 29 is a first terminating resistor, 30 is a second terminating resistor, 31 is a first short stub, and 32 is a second short stub.

Next, the operation of the above high frequency mixer circuit will be described. The high frequency signal input from the high frequency signal input terminal 1 is supplied to the first waveguide / microstrip line converter 4
Is converted from the waveguide mode to the mode of the microstrip line, propagates through the first microstrip line 13 and the high-frequency signal input matching circuit 10, and is applied to the FET mixer or the diode mixer 7. Here, the first terminating resistor 29 connected to the first microstrip line 13 is connected to a first short stub 31 whose electrical length is ¼ wavelength of a high frequency signal,
Since it is open to the high frequency signal, the high frequency signal does not propagate. Further, the local oscillator signal input from the local oscillator signal input terminal 2 is converted from the waveguide mode to the microstrip line mode by the second waveguide / microstrip line converter 5, and the second microstrip line mode is obtained. 14 and the input matching circuit 11 for local signal
It is applied to the T mixer or the diode mixer 7. Here, the second terminating resistor 30 connected to the second microstrip line 14 has an electrical length of 1/1 / the local oscillator signal.
The short stub 32 having the four wavelengths is connected to the second short stub 32, which is open to the local oscillator signal, so that the local oscillator signal does not propagate. The FET mixer or the diode mixer 7 converts a high frequency signal into an intermediate frequency signal which is a frequency component of the difference between the high frequency signal and the local oscillation signal. The intermediate frequency signal propagates through the intermediate frequency signal output matching circuit 12 and the transmission line 6, and is taken out from the intermediate frequency signal output terminal 3.

On the other hand, the intermediate frequency signal leaking to the high frequency signal input matching circuit 10 side must be directly propagated to the high frequency signal input matching circuit 10 for the first LPF 8 that selectively passes the intermediate frequency signal. There is no. But the first L
A reflected wave is generated at the first grounding point 15 of the intermediate frequency signal propagating through the PF 8, and reaches the first terminating resistor 29 via the first LPF 8 and the high frequency signal input matching circuit 10. The first terminating resistor 29 absorbs the reflected wave and does not cause resonance. Also, the input matching circuit 11 for the local oscillator signal
The intermediate frequency signal leaking to the side does not directly propagate to the local oscillator signal input matching circuit 11 because of the second LPF 9 that selectively passes the intermediate frequency signal. However, the intermediate frequency signal propagating through the second LPF 9 causes a reflected wave at the second ground point 16, and the reflected wave is generated in the second terminating resistor 30 via the second LPF 9 and the local signal input matching circuit 11. To reach. The second terminating resistor 30 absorbs the reflected wave, so that resonance does not occur. Therefore, no resonance appears in the intermediate frequency signal.

Thus, the electrical length from the first ground point 15 to the first waveguide / microstrip line converter 4 and the second ground point 16 to the second waveguide / microstrip line Even if the electrical length up to the converter 5 cannot be made equal to or less than ¼ wavelength of the intermediate frequency signal band, resonance can be prevented in the intermediate frequency signal of the high frequency mixer circuit by using the terminating resistor grounded by the short stub. it can.

[0038]

As described above, according to the high frequency mixer circuit of the first aspect of the invention, by providing the capacitors on the microstrip line through which the high frequency signal is propagated and the microstrip line through which the local oscillation signal is propagated, resonance is achieved. The resonance frequency can be moved outside the band of the desired intermediate frequency signal by moving one position of the reflection points causing the change of the distance between the reflection points.

Further, according to the high frequency mixer circuit of the second invention, the chip capacitor, the MIM capacitor and the ID capacitor are provided in the microstrip line through which the high frequency signal is propagated and the microstrip line through which the local oscillation signal is propagated. Since one of the reflection points that causes resonance is moved to change the distance between the reflection points, the resonance frequency can be moved outside the band of the desired intermediate frequency signal.

According to the high frequency mixer circuit of the third invention,
By providing a coupler on the microstrip line through which a high-frequency signal is propagated and the microstrip line through which a local signal is propagated, one of the reflection points causing resonance is moved and the distance between the reflection points is changed. The frequency can be moved outside the band of the desired intermediate frequency signal.

Further, according to the high frequency mixer circuit of the fourth invention, the grounded LPF at one end for passing the intermediate frequency signal and blocking the high frequency signal is connected to the microstrip line through which the high frequency signal is propagated. By connecting the grounded LPF, which passes the intermediate frequency signal and blocks the local oscillation signal, at one end to the microstrip line through which the local oscillation signal is propagated, one position of the reflection point that causes resonance is moved and between the reflection points. Since the distance is changed, the resonance frequency can be moved outside the band of the desired intermediate frequency signal.

According to the high frequency mixer circuit of the fifth invention,
Suppresses one reflection that causes resonance by connecting a terminating resistor that terminates the intermediate frequency signal whose one end is connected to the short stub to the microstrip line in which the high frequency signal is propagated and the microstrip line in which the local signal is propagated, respectively. By doing so, resonance in the intermediate frequency signal can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a high-frequency mixer circuit according to the present invention.

FIG. 2 is a diagram showing a second embodiment of a high frequency mixer circuit according to the present invention.

FIG. 3 is a diagram showing a third embodiment of a high frequency mixer circuit according to the present invention.

FIG. 4 is a diagram showing a fourth embodiment of a high frequency mixer circuit according to the present invention.

FIG. 5 is a diagram showing a fifth embodiment of a high frequency mixer circuit according to the present invention.

FIG. 6 is a diagram showing a sixth embodiment of a high frequency mixer circuit according to the present invention.

FIG. 7 is a diagram of a conventional high-frequency mixer circuit.

[Explanation of symbols]

1 High frequency signal input terminal, 2 Local signal input terminal, 3
Intermediate frequency signal input terminal, 4 first waveguide / microstrip line converter, 5 second waveguide / microstrip line converter, 6 transmission line, 7 FET mixer or diode mixer, 8 first LPF , 9 Second LPF, 10 High frequency signal input matching circuit, 11 Local signal input matching circuit, 12 Intermediate frequency signal input matching circuit, 13 First microstrip line, 14 Second microstrip line, 15 1st grounding point, 16 2nd grounding point, 17 1st chip capacitor, 18 2nd
Chip capacitor, 19 first MIM capacitor,
20 2nd MIM capacitor, 21 1st ID capacitor, 22 2nd ID capacitor, 23 1st coupler, 24 2nd coupler, 25 3rd LPF, 2
6 4th LPF, 27 3rd grounding point, 28 4th grounding point, 29 1st open stub, 30 2nd open stub, 31 1st termination resistance, 32 2nd termination resistance.

Claims (5)

[Claims] 1. A first waveguide / to which a high-frequency signal is input
Microstrip line converter, second waveguide / microstrip line converter to which local signal is input, transmission line to which intermediate frequency signal is output, mixer having high frequency signal terminal and local signal terminal A first low-pass filter connected to the high frequency signal terminal of the mixer and having one end passing the intermediate frequency signal frequency grounded; and one end connected to the local signal terminal of the mixer, passing the intermediate frequency signal frequency A second low-pass filter whose ground is grounded, a high-frequency signal input matching circuit, a local oscillator signal input matching circuit, an intermediate frequency signal output matching circuit, the high-frequency signal input matching circuit, and the first conductor. A first microstrip line connecting the wave tube / microstrip line converter, and a ground point of the first low-pass filter on the first microstrip line. Of the intermediate frequency signal band by Luo electrical length 1 /
It is provided at a position of 4 wavelengths or less and allows high-frequency signals to pass.
A first capacitor that blocks an intermediate frequency signal; a second microstrip line that connects the local signal input matching circuit and the second waveguide / microstrip line converter; A second capacitor, which is provided on the microstrip line at a position that is less than a quarter wavelength of the intermediate frequency signal band in terms of electrical length from the ground point of the second low-pass filter, allows local signals to pass through, and blocks intermediate frequency signals. A high-frequency mixer circuit comprising: 2. A chip capacitor, MIM (Metal Insulator) as the first and second capacitors.
or Metal) capacitor or an interdigital capacitor is used, The high frequency mixer circuit according to claim 1. 3. A first waveguide / to which a high frequency signal is input
Microstrip line converter, second waveguide / microstrip line converter to which local signal is input, transmission line to which intermediate frequency signal is output, mixer having high frequency signal terminal and local signal terminal A first low-pass filter connected to the high frequency signal terminal of the mixer and having one end passing the intermediate frequency signal frequency grounded; and one end connected to the local signal terminal of the mixer, passing the intermediate frequency signal frequency A second low-pass filter whose ground is grounded, a high-frequency signal input matching circuit, a local oscillator signal input matching circuit, an intermediate frequency signal output matching circuit, the high-frequency signal input matching circuit, and the first conductor. A first microstrip line connecting the wave tube / microstrip line converter, and a ground point of the first low-pass filter on the first microstrip line. Of the intermediate frequency signal band by Luo electrical length 1 /
It is provided at a position of 4 wavelengths or less and allows high-frequency signals to pass.
A first coupler for cutting off an intermediate frequency signal; a second microstrip line for connecting the local matching signal input matching circuit and the second waveguide / microstrip line converter; The above second on the microstrip line
A low-pass filter having a second coupler that is provided at a position that is an electrical length less than or equal to a quarter wavelength of the intermediate frequency signal band from the ground point and that passes the local oscillation signal and blocks the intermediate frequency signal. High frequency mixer circuit. 4. A first waveguide / into which a high frequency signal is input
Microstrip line converter, second waveguide / microstrip line converter to which local signal is input, transmission line to which intermediate frequency signal is output, mixer having high frequency signal terminal and local signal terminal A first low-pass filter connected to the high frequency signal terminal of the mixer and having one end passing the intermediate frequency signal frequency grounded; and one end connected to the local signal terminal of the mixer, passing the intermediate frequency signal frequency Grounded second low-pass filter, high-frequency signal input matching circuit, local signal input matching circuit, intermediate frequency signal output matching circuit, high-frequency signal input matching circuit, and first waveguide And a first microstrip line connecting the microstrip line converter and the first microstrip line, and is connected to the first microstrip line, A third low-pass filter that has a ground point at a position that is an electrical length less than or equal to 1/2 wavelength of the intermediate frequency signal band from the point and that passes the intermediate frequency signal frequency, the local oscillator signal input matching circuit, and the second A second microstrip line connecting the waveguide / microstrip line converter and the second microstrip line are connected to the second low-pass filter from the ground point of the intermediate frequency signal band with an electrical length. A high-frequency mixer circuit having a fourth low-pass filter having a ground point at a position of ½ wavelength or less and passing an intermediate frequency signal frequency. 5. A first waveguide / to which a high frequency signal is input
Microstrip line converter, second waveguide / microstrip line converter to which local signal is input, transmission line to which intermediate frequency signal is output, mixer having high frequency signal terminal and local signal terminal A first low-pass filter connected to the high frequency signal terminal of the mixer and having one end passing the intermediate frequency signal frequency grounded; and one end connected to the local signal terminal of the mixer, passing the intermediate frequency signal frequency Grounded second low-pass filter, high-frequency signal input matching circuit, local signal input matching circuit, intermediate frequency signal output matching circuit, high-frequency signal input matching circuit, and first waveguide / A first microstrip line connecting the microstrip line converter and the first microstrip line for terminating an intermediate frequency signal, There first termination resistor and, the local oscillation signal input matching circuit and the second waveguide first short stub is a quarter wavelength of the RF signal is connected to one end /
A second microstrip line for connecting to the microstrip line converter, and a second microstrip line connected to the second microstrip line for terminating the intermediate frequency signal and having an electrical length of ¼ wavelength of the local oscillation signal. 2. A high-frequency mixer circuit, comprising: a second terminating resistor having a short stub connected to one end thereof.